SCIENTIFIC ARTICLES
Stomatologija, Baltic Dental and Maxillofacial Journal, 13: 55-61, 2011
Comparative analysis of CRT Buffer, GC Saliva Check
Buffer tests and laboratory titration to evaluate saliva
buffering capacity
Ilze Maldupa, Anda Brinkmane, Anna Mihailova
SUMMARY
Objective. The purpose of this study is to evaluate the ability of two commercial strip tests
and laboratory titration to detect saliva buffer capacity.
Materials and methods. Sixty-four patients were examined. Stimulated saliva was collected
and buffer capacity was determined with two different chair-side strip tests in addition to immediate transportation to the laboratory to check the buffering ability by titrating with 0.005 M
HCl and measuring pH by digital pH/Ion meter, used as a gold standart. The correlation were
analyzed using the Spearman Rank Correlation Test, Cohen’s Kappa coef cient and Pearson’s
Correlation test, p<0.01. Sensitivity and specicity were used to measure precision of these tests.
Results. The response rate was 80%. High buffer capacity was found in 23.4% of cases,
medium in 62.5%, and low in 14.1%. The Spearman Rank Correlation coefcient between the
titration method and CRT Buffer test was 0.685 and the GC Saliva Check Buffer was 0.837. The
Kappa coefcient for the CRT Buffer test was 0.508, while the coefcient for the GC Saliva
Check Buffer was 0.752. The Pearson Correlation for the GC Saliva Check was 0.675. The
difference is found in the buffer capacity at initial pH and at pH value 3.
Conclusions. Both colorimetric tests correlate with the acid titration method in laboratory
and are usable for saliva buffer capacity detection in dental of ces. Buffer capacity detected in
laboratory at different pH values can provide more information regarding caries risk.
Key words: saliva, caries risk, buffer capacity.
INTRODUCTION
Caries risk assessment has become a commonly
used term both among researchers and in practical
dentistry. Due to the fact is that caries is a multifactorial disease, to determine caries risk detailed
information about patient should be collected, including saliva properties [1].
Saliva is essential for the lifelong conservation
of dentition. There are various functions of saliva:
tooth surface protection through a lm of salivary
mucins and proline-rich glycoprotein; a re-minerDepartment of Therapeutic Dentistry, Institute of Stomatology,
Riga Stradins University, Latvia
*
Ilze Maldupa* – PhD student
Anda Brinkmane* – D.D.S., PhD., assoc. prof.
Anna Mihailova* – postgraduate student
Address correspondence to Dr. Ilze Maldupa, T. Grothusa str. 2,
Jelgava, LV – 3002.
E-mail address: [email protected]
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
alisation function by attracting calcium, phosphate
and uoride ions; IgA, IgM, IgG, enzymes and other
proteins ensure antibacterial function; and with bicarbonate, phosphate and protein buffer systems in
saliva it also has a buffering ability [2].
Ericsson in 1959 wrote a review of 21 reports
that appeared prior to 1956 and found caries experience connectivity to saliva buffer capacity
[3]. Additionally, the Vipeholm study showed that
caries-active patients had a lower buffer capacity
than caries-inactive patient [4].
Buffer Capacity is the mmoles of NaOH or HCl
per mL of buffer solution needed to produce a unit
change in pH [5]. In saliva, we are interested in
its buffering ability against acids. Salivary glands
produce buffer systems in saliva, from which the
most important bicarbonate system is produced
from CO2. The bicarbonate level in plasma is about
20 – 25 mmol / l, in un-stimulated saliva it is about
55
I. Maldupa et al.
ten times lower – during stimulation, however,
glandular cells increase CO2 production, increasing bicarbonate concentration and thereby making
it closer to plasma concentration. With very high
stimulation the bicarbonate concentration may even
exceed the plasma level [6, 7]. It is also important
to know that a reduction of the bicarbonate level in
saliva reduces the saliva secretion rate [8], thus the
buffer capacity is considered to be one of the most
important factors for reducing secretion rate. Since
the bicarbonate concentration is lower and the saliva
ow rate can’t provide buffer systems penetration
in dental plaque, the plaque buffering ability is also
reduced and the pH value falls to more acidic. That
means there are more H+ ions in an individual’s
plaque that cause demineralization. Such plaque has
a reduced ability to accumulate Ca and P [9, 10], so
also re-mineralization possibilities are decreased.
In 1959, Ericsson developed a test [3] that could
be used in laboratories or by researchers, but is too
complicated and time-consuming a procedure for
clinical practice [11]. There are several commercial buffer capacity diagnostic tests now available
in the world market, but unfortunately there is no
ideal test and the tests have varying prices and usage simplicity.
Therefore, the aim of the study was to evaluate
the ability of two commercial strip tests and titration
in laboratory to detect saliva buffer capacity.
MATERIALS AND METHODS
Study subjects
The study population involved 64 individuals
aged from 24 to 62 years-old. This research received
ethical approval from the Riga Stradins University
Ethics Committee. All patients signed an agreement
prior to entry into the study. There were 80 individuals invited, of which 64 agreed to the terms and were
involved in study.
A questionnaire about age, gender, general
diseases, drug use, diet and hygiene habits [1] was
lled out for all participants. The survey was in the
form of an interview focusing on general diseases
and drug use, which could inuence saliva  ow rate
and buffer capacity. Diet and drinking habits were
also registered in detail.
Clinical examination involved the DNFT index
according to the WHO criteria.
SCIENTIFIC ARTICLES
ing gum for at least 2 h and to rinse their mouths at
least 1 h before examination [3, 12, 13]. Patients sat
upright in a relaxed position with their heads tilted
down [14] and started to chew parafn wax. The
rst portion of saliva was swallowed, then time was
taken for 5 minutes [15, 16], during which patients
were instructed not to swallow, but collect all saliva
in a container. Saliva was divided into two parts:
1) 5 ml of saliva was collected in plastic containers
and within one hour transported to the laboratory;
2) the rest of the saliva was used for buffer capacity
determination by the GC Saliva-Check Buffer test
and the CRT Buffer test.
CRT Buffer test
With a pipette a saliva sample was taken from
the collection cup, and 1 drop was dispensed onto a
test pad. After waiting the 5 minutes recommended
by the manufacturers, the  nal color was detected
and buffering ability was assessed. Blue color means
high buffer capacity, green means medium and yellow means low.
GC Saliva-Check Buffer
Using a pipette, a saliva sample was taken and 1
drop was placed on each of the 3 test pads. Test pads
began to change color immediately, but the nal color
was only detected after 2 minutes. Then the result
was calculated by adding the points according to
the nal color of each pad: green – 4 points; green/
blue – 3 points, blue – 2 points, red/blue – 1 point,
red – 0 points. All points were counted and result was
determined: 0 – 5 points as very low buffering ability,
6 – 9 points as low, 10 – 12 points as normal/high.
Saliva sampling
Saliva was stimulated by chewing paraffin
wax and then collected from individuals who were
instructed not to drink, eat, smoke, or chew chew-
Acid titration
In the laboratory 5 ml of saliva was collected
into a special cup to maximize the contact area of
the pH-sensitive electrode with saliva. The initial
pH was measured by using a pH-sensitive electrode
[17]. Then, using a precise burette, 0,5 ml of 0,005
M HCl was added to the test saliva and allowed to
stabilize for a few seconds, after which the pH was
measured again. The saliva sample was constantly
stirred using a magnetic stirrer and glass rod [18].
The process was continued until the pH decreased
by 1 unit. Then the buffer capacity was calculated
using the formula CHCl ´ VHCl / ΔpH ´ Vsaliva, where CHCl
means concentration of HCl, VHCl means volume of
HCl, ΔpH means pH changes from initial, and Vsaliva
represents volume of saliva sample [5].
The same process was continued until the pH
decreased to a value of 3, and again buffering ability
was calculated using the same formula.
56
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
SCIENTIFIC ARTICLES
I. Maldupa et al.
Data analysis
The unit of measurement for buffering ability is
mmol HCl / 1 liter saliva to decrease pH by 1 unit
[5]. GC company includes these values in its colorimetric scale, and just after detecting the buffering
ability value it is possible to detect whether the
buffering ability is very low (buffer capacity 0 – 5),
low (6 – 9) or high (10 – 12). The same values were
calculated after titrating with 0,005 M HCl, and
results were divided into 3 groups according to the
previous mentioned system.
The manufacturers had interpreted test results in
different ways. CRT Buffer test has been designed
to detect high, medium and low buffer capacity,
while GC Saliva Check Buffer divided results into
normal/high, low and very low. As both tests use 3
groups, it was decided to divide all results into high,
medium and low buffer capacity [19].
The correlation of ranking results of CRT Buffer, GC Saliva Check Buffer tests and titration were
analyzed using the Spearman Rank Correlation
Test and Cohen’s Kappa coef cient, while the correlation of scale data, which was possible for GC
Saliva Check Buffer and titration, were detected by
Pearson’s Correlation test, p<0.01.
To analyze colorimetric methods, results from
the titration method with HCl were defined as
“true” scores. Medium and low buffering ability
were de ned as “positive” cases (as the test showed
a deviation from normal buffer capacity), while
high cases were de ned as “negative” (as the test
indicated a normal buffer capacity). After measuring the buffer capacity with colorimetric tests, true
positive cases (TP) were dened as medium and
low scores when titration also detected as medium
and low. False positive cases (FP), by contrast,
were when colorimetric test indicated medium or
low score, but titration indicated a high buffering
ability. True negative cases (TN) were dened as
when colorimetric tests indicated high capacity, as
did titration method. False negative cases (FN) were
where chair-side tests indicated high capacity, but
titration with acid revealed medium or low buffering
ability. Sensitivity was calculated by TP / (TP + FN).
Speci city: TN / (TN + FP) [20].
To detect whether there are signi cant differences between different tests and the buffering
ability in neutral saliva and at pH 3, the Paired
samples Student T – test was used. We considered
as signi cant any value of p<0.05.
The null hypothesis is that there is no correlation between commercial tests and the precise titration method in laboratory.
RESULTS
Table 1. Titration method and CRT Buffer test crosstabulation
Titration high buffer
method capacity
medium buffer
capacity
low buffer
capacity
Total
CRT Buffer
high
medium
buffer
buffer
capacity capacity
14
1
low
buffer
capacity
0
Total
11
25
4
40
0
3
6
9
25
29
10
64
15
Table 2. Titration method and GC Saliva Check Buffer Crosstabulation
GC Saliva Check Buffer
high
medium
buffer
buffer
capacity capacity
Titration high buffer
15
0
method capacity
medium buffer
4
33
capacity
low buffer
0
2
capacity
Total
19
35
low
buffer
capacity
0
Total
3
40
7
9
10
64
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
15
From an invited 80 patients, 64
(80%) agreed to take part in the study.
The mean age of participants was 36
years.
From 64 saliva samples titration
showed a high buffer capacity in 15
cases (23.4%), medium in 40 cases
(62.5%), and the remaining 9 (14.1%)
subjects were classied as having a
low buffering ability. Both colorimetric tests had different results – for the
CRT Buffer test, 19 from 64 cases had
results divergent from laboratory measurements. For the GC Saliva Check
Buffer just 9 cases showed divergent
results (Table 1, 2).
The Spearman Rank Correlation
indicated a positive coefcient between
the titration method and both the CRT
Buffer test (rs=0.685) and the GC Saliva
Check Buffer (rs=0.837). The Kappa
coefcient, however, showed a positive correlation for the CRT Buffer test
(k=0.508) and strong correlation for
the GC Saliva Check Buffer (k=0.752).
57
I. Maldupa et al.
SCIENTIFIC ARTICLES
Fig. 1. Mean buffer capacity detected by using acid titration
method at initial pH value and at pH value 3
Fig. 2. Buffer capacity changes from initial pH to pH value 3
It is possible to get parametric variables for
titration method and GC Saliva Check Buffer
test, though the Pearson Correlation was detected
(r=0.675), which showed a high correlation as well.
Both colorimetric tests had acceptable accuracy,
but the GC Saliva Check Buffer test has a higher sensitivity (0.87) and specicity (0.83) than the CRT Buffer
test (sensitivity – 0.69, specicity – 0.74) (Table 3).
The difference is found between buffer capacity at
initial pH (lowering pH by 1 unit from initial pH, mean
buffering ability was 7.74 ml HCl / l saliva) and at pH
value 3 (lowering pH from initial pH till pH value 3,
mean buffering ability was 5.58 ml HCl / l saliva) (Figure 1). Paired samples T test showed a signicant difference between these two buffer capacity mean values.
It was calculated that just 13.3% (2) of the subjects with high buffer capacity also had high buffering
ability at pH value 3, but for 80% (12) of the high
capacity patients it changed to medium – and even
to low buffering ability for 6.7% (1) of participants.
Also, 65% (26) of medium capacity patients observed
a lowering of buffering capacity (Table 4) (Figure 2).
In the current study there no correlation was
found between buffer capacities, detected either by
the two colorimetric tests or by the acid titration
method at initial pH value and DMFT. There was
also no correlation between buffer capacity at different pH values and caries prevalence at condence
level p<0.01, but there was a negative correlation between caries prevalence and buffer capacity changes
from initial pH and at pH value 3 at condence value
p<0.05 (r=-0.310) (Table 5).
This study compared two different colorimetric
saliva buffer capacity tests and the acid titration
method in laboratory. It is important that the real
buffering ability of the saliva was detected, which
gives more information than just a relative ranking
of high, medium or low buffer capacity.
Ericsson in 1959 reported that there were differences in the saliva buffering capacity of caries
free and caries active patients [3]. He developed a
saliva buffer capacity test, which showed that the
nal pH is an acceptable measure of saliva buffering
ability. In more recent decades different companies
have developed test strips that gave possibilities to
detect buffer capacity in a dental of ce, as it is economical and time-effective. Different studies have
been made to measure precision of chair-side, int.
al. colorimetric tests, detecting correlation with the
Ericsson method [11, 19, 21]. Kitasako et. al. found
the highest correlation for a quantitative test using
a hand-held pH meter [11]. In another publication
the same researchers concluded that the Adapted
Checkbuf test is also useful for measuring buffer
capacity in resting saliva, as this test displayed the
highest agreement with Ericsson method [19].
In the present study, the correlation of colorimetric tests and titration was calculated using different statistical methods. From the CRT Buffer it
is possible just to get ranking results and it is also
possible to convert results from other tests into ranks
of high, medium and low buffer capacity. For such
results the Spearman Rank Correlation Test and
Kappa coef cient showed a higher value for the
GC Saliva Check Buffer test. Pearson’s Correlation coefcient showed weaker, but still acceptable,
agreement between laboratory results and the GC
Saliva Check Buffer test as a scale data are obtainable from these tests, but it isn’t possible to compare
with the CRT Buffer as Pearson’s Correlation test
is just for scale data.
58
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
DISCUSSION
SCIENTIFIC ARTICLES
I. Maldupa et al.
Fig. 3. Buffer curve for two patients, both had high buffer
capacity detected at initial pH value
Comparing the Spearman Rank and the Kappa
correlation coefcients, as well as the sensitivity
and speci city of colorimetric tests, the GC Saliva
Check Buffer test showed better results in absolute
Table 3. Sensitivity and specicity of CRT Buffer and GC
Saliva Check Buffer
CRT Buffer
True positive cases
True negative cases
False positive cases
False negative cases
Sensitivity
Specicity
31
14
5
14
0.69
0.74
GC Saliva
Check Buffer
40
15
3
6
0.87
0.83
Table 4. Buffer capacity changes from initial pH to pH value
3 (acid titration method)
High - high
High - medium
High - low
Medium - medium
Medium - low
Low - low
Frequency
2
12
1
14
26
9
Percent
3,1
18,8
1,6
21,9
40,6
14,1
Table 5. Correlation between saliva buffer capacity detected
by different tests and caries prevalence
Buffer CRT
capacity Buffer
changes
-0.310
-0.099
Pearson
Correlation
p value
0.036
Low - low
0.513
GC Saliva
Check
Buffer
-0.119
Titration
method at
initial pH
-0.198
0.432
9
0.188
14,1
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
numbers than the CRT Buffer test, but the Paired
samples T test didn’t show a signicant difference
between the results of these tests (p>0.01).
In the current study buffer capacity is detected
by using acid titration. Ability is not calculated according to pH value, but by buffering capacity stated
by mmol HCl on 1 liter of saliva to decrease pH by
1 unit. Figure 3 shows how pH decreases by adding
acid, and it also shows that in both patients buffer
capacity is high, both needed aprox. 20 ml HCl to
reach a pH decrease of 1 unit, but for the  rst case
decreasing pH by one more unit it was necessary
to add just 5 ml while for second case 10 ml was
needed. That means if rst patient would have a
lower initial pH value, buffering ability would also
be lower.
The composition of un-stimulated saliva differs
from stimulated. As more saliva is stimulated it
becomes more similar to the composition of plasma
[13]. For example, an increase in the salivary  ow
rate, obtained by the stimulation of acidic food,
increases the concentration of sodium, chloride
and bicarbonate and decreases the concentrations
of salivary potassium and phosphate, compared
with un-stimulated saliva [22-24]. As in stimulated
saliva, as the concentration of bicarbonates becomes higher and closer to plasma concentration,
the bicarbonate system plays a major role in buffer
capacity [18] - but at lower pH values phosphate and
protein systems are also taking part in the buffering
process. As these systems have a lower buffering
ability, pH also decreases more rapidly at lower pH
values [18]. This explains why the buffering ability
at the initial pH value is higher than at pH 3, as was
shown in this study.
Saliva provides a cleansing of teeth, provides
an optimal pH in which all chemical reactions are
carried out and moreover saliva has protective functions – one of these is buffering ability, the signicance of which is questionable. In most investigations, as well as in this study, buffer capacity tests
show weak or negligible correlation to caries experience [6, 25, 26]. The reasons for this could be that
colorimetric tests are used in an atmosphere high in
carbon dioxide and thus the bicarbonate buffer system could be lost, and remaining is mostly phosphate
and protein buffer systems which provide only weak
buffering ability [18]. Saliva’s buffer capacity role is
also discussed because saliva is not always in direct
contact with the surface of teeth, as there is peliqula
or plaque and the demineralization process take
place in the plaque and below the enamel surface,
where the buffering mechanisms are different from
those in saliva [27]. But Stralfors [18] has veried
59
I. Maldupa et al.
that the buffering power in saliva is similar for that
in plaque and Malekipour et al [28] have proved in
clinical trial that saliva titration curves for patient
with active caries differs from the pattern of caries
free subjects. In literature more investigations could
be found, which have proved a negative correlation
between buffering and parameters measuring different aspects of dental caries [3, 29-33].
As saliva buffer capacity has an impact on
plaque buffer capacity, it is denitely important to
detect it in dental ofces as a caries risk factor. In
the current study there is only a weak correlation
between buffer capacity changes (from buffer capacity at the initial pH level to a pH value 3) and
the DMFT index, and no correlation between usual
detected buffer capacity at the initial pH level by
using either the precise acid titration method in
laboratory or by chair-side colorimetric tests – the
CRT Buffer and the GC Saliva Check Buffer. The
reason could be a small sample size that limits the
results of this research. It would be reasonable to
get more information about a possible correlation
with caries prevalence or caries risk by increasing
sample size. Nevertheless it may be a signicant
nding that there were weak correlations for average buffer capacity detected as pH decreases to
pH value 3, as also Driezen in 1946 recommended
detecting buffering ability by measuring the amount
SCIENTIFIC ARTICLES
of 0.01N lactic acid required to reduce the pH from
its normal level to pH 4 [34]. And Coogan and
MacKeown found signi cant differences in buffering capacity for groups with no new decays during
the past 4 years as compared to groups with higher
caries activity, using a modied Dreasen test [35],
while other investigators using the colorimetric test
GC Saliva Check Buffer found no correlation with
caries prevalence scored using DMFT [36] as in the
current study. But a weak negative correlation was
found with ICDAS (international caries detection
and assessment system) scores 3 and 4, as it is a
more precise caries detection system [36].
CONCLUSIONS
This study demonstrates that the null hypothesis
has been rejected and that both colorimetric tests
correlate with the acid titration method in laboratory. This why chair-side diagnostic tests are usable
for saliva buffer capacity detection in dental ofces.
This study shoved that the GC Saliva Check Buffer
has higher accuracy than CRT Buffer test.
Saliva buffer capacity gives more information
if detected in different pH values as it changes and
decreases with lower pH values. Buffer capacity
detected at different pH values also showed higher
impact on caries prevalence.
REFERENCES
1. Bratthall D. Dental Caries: Intervenned – Interrupted – Interpreted. Eur J Oral Sci 1996;104:415-91.
2. Van Nieuw Amerongen A, Bolscher JG, Veerman EC. Salivary proteins: protective and diagnostic value in cariology.
Caries Res 2004;38:247-53.
3. Ericsson Y. Clinical investigations of the salivary buffering
action. Acta Odontol Scand 1959;17:131-65.
4. Gustafsson BE, Quensel CE, Lanke LS, Lundqvist C, Grahnen H, Bonow BE, Krasse B. The Vipeholm dental caries
study; the effect of different levels of carbohydrate intake
on caries activity in 436 individuals observed for  ve years.
Acta Odontol Scand 1954;11:195-206.
5. Wohlt JE, Jasaitis DK, Evans JL. Use of acid and base titrations to evaluate the buffer capacity of ruminant feedstuffs
in vitro. J Dairy Sci 1987;70:1465-70.
6. Fejerskov O, Kidd EAM. Dental Caries The Disease and
its Clinical Management. Blackwell; 2003.
7. Kivelä J, Laine M, Parkkila S, Rajaniemi H. Salivary carbonic anhydrase VI and its relation to salivary  ow rate and
buffer capacity in pregnant and non-pregnant women. Arch
Oral Biol 2003;48:547-51.
8. Dawes C. Physiological factors affecting salivary ow rate,
oral sugar clearance, and the sensation of dry mouth in man.
J Dent Res 1987;66:648-53.
9. Pearce EIF, Hancock EM, Gallagher IHC. The effect of
 uorhydroxyapatite in experimental human dental plaque
on its pH, acid production and soluble calcium, phosphate
and  uoride levels following glucose challenge. Arch Oral
Biol 1984;29:521-7.
10. Zuniga MA, Lopez H, Sandham HJ, Bradley EL, Koulourides T. Calcium and phosphorus contents of dental plaques
and microhardness changes of sample enamel in the human
mouth. Ala J Med Sci 1973;10:3-10.
60
11. Kitasako Y, Burrow MF, Stacey M, Huq L, Reynolds EC,
Tagami J. Comparative analysis of three comercial saliva
testing kits with a standard saliva buffering test. Austr Dent
J 2008;53:140-4.
12. Hong-Seop K, Sung-Woo L, Sung-Chang C, Young-Ku K.
Oral manifestations and salivary ow rate, pH and buffer
capacity in patients with end-stage renal disease undergoing
hemodialysis. Oral Surg Oral Med Oral Pathol Oral Radiol
Endod 1999;88:316-9.
13. Chiappin S, Antonelli G, Gatti R, Palo E. Saliva specimen:
a new laboratory tool for diagnostic and basic investigation.
Clin Chim Acta 2007;383:30-40.
14. Navazesh M, Christensen CM. A Comparison of whole
mouth resting and stimulated salivary measurement procedures. J Dent Res 1982;61:1158-62.
15. Laine M, Pienihakkinen K, Leimola-Virtanen R. The effect
of repeated sampling on paraf n-stimulated salivary  ow
rates in menopausal women. Arch Oral Biol 1999;44:93-5.
16. Meurman J.H., Rantonen P., Pajukoski H., Sulkava R. Salivary albumin and other constituents and their relation to oral
and general health in the elderly. Oral Surg Oral Med Oral
Pathol Oral Radiol Endod 2002;94:432-8.
17. Heintze U, Birkhed D, Bjorn H. Secretion rate and buffer
effect of resting and stimulated whole saliva as a function
of age and sex. Swed Dent J 1983;7:227-38.
18. Lilienthal B. An analysis of the buffer systems in saliva. J
Dent Res 1955;34:516-30.
19. Kitasako Y, Burrow MF, Huq LN, Stacey MA, Reynolds
EC, Tagami J, et al . a simpli ed quantitative test adapted
checkbuf test for resting saliva buffering capacity compared
with a standard test. Oral Surg Oral Med Oral Pathol Oral
Radiol Endod 2009;108:551-6.
20. Richard D, Clarkson J, Matthews D, Niederman R. Evi-
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
SCIENTIFIC ARTICLES
dence – based Dentistry: Managing Information for Better
Practice. London: Quintessence Publ. Co. Ltd.; 2008.
21. Moritsuka M, Kitasako Y, Burrow MF, Ikeda M, Tagami J,
Nomura S. Quantative assessment for stimulated saliva ow
rate and buffering capacity in relation to different ages. J
Dent 2006;34:716-20.
22. Jensdottir T, Nauntofte B, Buchwald C, Bardow A. Effects
of sucking acidic candy on whole-mouth saliva composition.
Caries Res 2005;39:468-74.
23. Aps JKM, Martens LC. Review: The physiology of saliva and transfer of drugs into saliva. Forensic Sci Int
2005;150:119-31.
24. Sreebny LM. Saliva in health and disease: an appraisal and
update. Int Dent J 2000;50:140-61.
25. Wilson RF, Ashley FP. Identication of caries risk in schoolchildren: salivary buffering capacity and bacterial counts,
sugar intake and caries experience as predictors of 2-year
and 3-year caries increment. Br Dent J 1989;167:99-102.
26. Sullivan A. Correlation between caries incidence and secretion rate/buffer capacity of stimulated whole saliva in
5-7-year-old children matched for lactobacillus count and
gingival state. Swed Dent J 1990;14:131-5.
27. Dibdin GH, Shellis RP. The interpretation of CO2 equilibration
data to obtain plaque uid buffer capacities, and comparison
with results obtained by titration. J Dent Res 1989;68:1323-7.
28. Malekipour MR, Manoochehr M, Shirani F. Buffering capacity of saliva in patients with active dental caries. Asian
I. Maldupa et al.
J Biochem 2008;3:280-3.
29. Lagerlöf F, Oliveby A. Caries-protective factors in saliva.
Adv Dent Res 1994;8:229-38.
30. Onozawa H, Yasui T, Nakao S. A study on the relationship between selected oral environmental factors and the
caries type in infants. Meikai Daigaku Shigaku Zasshi
1990;19:122-6.
31. Ravald N, Birkhed D. Factors associated with active and
inactive root caries in patients with periodontal didease.
Caries Res 1991;25:377-84.
32. Russel JI, Macfarlane TW, Aitchison TC, Stephen KW,
Burchell CK. Caries prevalence and microbiological and
salivary caries activity tests in Scottish adolescents. Community Dent Oral Epidemiol 1990;18:120-5.
33. Russel JI, Macfarlane TW, Aitchison TC, Stephen KW,
Burchell CK. Prediction of caries increment in Scotish
adolescents. Community Dent Oral Epidemiol 1991;19:74-7.
34. Driezen S, Mann AW, Cline JK, Spies TD. The buffer capacity of saliva as a measure of dental caries activity. J Dent
Res 1946;25:213-22.
35. Coogan MM, MacKeown JM., Galpin JS, Fatti LP. Microbiological impressions of teeth, saliva and dietary  bre can
predict caries activity. J Dent 2008;36:892-9.
36. Varma S, Banerjee A, Bartlett D. An in vivo investigation
of associations between saliva properties, caries prevalence
and potential lesion activity in an adult UK population. J
Dent 2008;36:294-9.
Received: 30 10 2010
Accepted for publishing: 24 06 2011
Stomatologija, Baltic Dental and Maxillofacial Journal, 2011, Vol. 13, No. 2
61